1. Technical Field
The present invention generally relates to a process for substantially removing residual catalyst components from crude organic products, e.g., crude polyalphaolefin polymerization products.
2. Description of the Related Art
Generally, in organic synthesis, catalysts are very often soluble in the resulting crude organic product and cannot be removed by simple filtration. For example, following the polymerization of an alphaolefin, the polyalphaolefin (PAO) polymerization product will contain dissolved catalyst, which needs to be removed prior to the step of hydrogenation. Accordingly, in finishing PAO, considerable amounts of money are spent on hydrogenation catalyst and hydrogen usage. Much of this cost is a direct result of the high residual polymerization catalyst levels remaining in the unfinished product, since the residual metal and halogen from the polymerization catalyst render higher hydrogenation catalyst loadings necessary during hydrogenation of the crude PAO product due to the hydrogenation catalyst being poisoned by the halogen.
The insufficient removal of catalysts, e.g., olefin polymerization catalysts, and, in particular, their metallic and halogen components, from a liquid organic product such as liquid olefin polymer also results in other undesirable problems. For example, the presence of catalyst residues may cause discoloration of the resulting polymerization products, the generation of hydrogen halide gas owing to the thermal degradation of the catalyst, the degradation or decomposition of the organic compounds owing to structural change during subsequent distillation, the poisoning by halogen contaminants of hydrogenation catalysts during subsequent polymer treatment, the formation of aluminum hydroxide slimes which are difficult to handle and the like.
Efforts have been made to remove olefin polymerization catalysts from the liquid olefin polymer. For example, U.S. Pat. No. 4,028,485 discloses a process for removing hydrogenation catalyst residue from solutions of hydrogenated olefins or olefinic polymers containing them comprising treating such solutions with a non-aqueous acid followed by neutralization with an anhydrous base and filtration. U.S. Pat. No. 4,122,126 discloses a method for removing an aluminum halide or its complex catalyst from a polymerization product comprising the steps of adding to the polymerization product an aprotic polar solvent in an amount of 1 through 6 mol per one mol of the aluminum halide in the catalyst present in the product and sufficiently mixing them at a temperature of 70° C. through 150° C., and then filtering the mixture at a temperature of 70° C. through 150° C. The addition of the aprotic polar solvent facilitates the separation of the catalyst from the polymerization product.
U.S. Pat. No. 4,476,297 discloses that the content of titanium and light metal halides and aluminum compounds in polyolefins emanating from the catalyst system can be considerably reduced by treatment with a higher, preferably branched, aliphatic monocarboxylic acid having 6 to 10 carbon atoms.
U.S. Pat. No. 4,642,408 discloses the removal of nickel, aluminum and chlorine derivatives, which remain dissolved in olefin oligomers after oligomerization in the presence of a catalyst containing such derivatives by treatment with oxygen or a gas containing oxygen, anhydrous ammonia, and a solution of an alkali metal hydroxide.
U.S. Pat. No. 4,701,489 discloses that the catalyst residues present in an on-purpose produced amorphous polyalphaolefin are deactivated by contacting the molten polymer with sufficient water to provide at least a 3:1 water/Al mole ratio and then the polymer is stabilized with a hindered phenolic antioxidant.
U.S. Patent Application Publication No. 2005/0101761 discloses a method for reducing levels of residual halogen and Group IIIb metals in a crude poly(alpha-olefin) polymerized in the presence of a catalyst comprising the halogen and Group IIIb metals, wherein the method comprises: (a) washing the crude poly(alpha-olefin) with water; (b) separating the aqueous and organic phases; (c) adding an adsorbent selected from the group consisting of magnesium silicates, calcium silicates, aluminum silicates, aluminum oxides, and clays to the organic phase to form a slurry; (d) heating the slurry under reduced pressure at a temperature of at least about 180° C. for at least about thirty minutes; and then (e) separating the adsorbent from the slurry. However, this water washing method is overly complicated, employs additional steps, e.g., decantation, filtration and drying, and produces a large amount of aqueous waste. It is also difficult to run on a continuous basis.
Additionally, in the production of styrene (also known as phenylethylene or vinylbenzene), ethylbenzene (EB) is formed by first alkylating benzene, by transalkylating polyethylbenzenes (PEBs), or by both in the presence of an alkylating catalyst, e.g., aluminum chloride, and then the EB is dehydrogenated to produce styrene. Styrene is an important monomer used in the manufacture of, e.g., plastics. As with the olefin polymerization catalysts discussed above, the insufficient removal of alkylating catalysts and, in particular, their halogen components, from the liquid ethylbenzene results in additional steps that require water which is problematic.
It would be desirable to provide an improved process for removing the catalyst residues from reaction products such as an olefin polymerization product or an alkylation reaction product, as fully as possible prior to subsequent treatment and/or use of such products.